Which of the following can be used as backfill outside a foundation WITHOUT being compacted

Which of the following can be used as backfill outside a foundation WITHOUT being compacted

• A. 3/4 minus gravel
• B. clean fill dirt
• C. soil without organic material
• D. controlled low strength material

Answer: (D)

Backfill around a foundation can be placed in two ways: materials that must be compacted to achieve the required density and bearing capacity, and a special type of flowable fill that is designed to be placed without mechanical compaction. Controlled Low Strength Material (CLSM) fits the latter. It’s a cementitious mix that flows into the space and is engineered to achieve a predictable, low compressive strength without the need for compaction, so it can be left in place around a foundation while still providing support and stability. The other options—gravel, clean fill dirt, and soil with no organic material—typically require compaction to reach the necessary density and bearing capacity; if compacted isn’t performed, they can settle or shift, risking foundation stability.

Backfill around a foundation can be placed in two ways: materials that must be compacted to achieve the required density and bearing capacity, and a special type of flowable fill that is designed to be placed without mechanical compaction. Controlled Low Strength Material (CLSM) fits the latter. It’s a cementitious mix that flows into the space and is engineered to achieve a predictable, low compressive strength without the need for compaction, so it can be left in place around a foundation while still providing support and stability. The other options—gravel, clean fill dirt, and soil with no organic material—typically require compaction to reach the necessary density and bearing capacity; if compacted isn’t performed, they can settle or shift, risking foundation stability.